This invention relates to latch assemblies for vehicle doors, particularly for light passenger and goods vehicles, incorporating power actuation for latching and/or unlatching.
Power operated locking and latching of doors is becoming more favoured, both as part of central locking systems, and to enable more effective weathersealing of doors and greater freedom in styling and design. Power actuated unlatching has the advantages of dispensing with much of the mechanical linkage and components needed for conventional manual inside and outside door handles, and in providing unitary lock and latch modules of standard form which can be speedily installed in doors of a wide range of vehicle models and types without special adaptation.
The object of the invention is to provide improvements in vehicle door latch assemblies, in particular the provision of latches having a power unlatching facility in an economical, effective and reliable form.
According to the invention there is provided a vehicle door latch assembly including pivotally mounted or other latch operatively co-acting with a striker as the door nears its closed position, a latching pawl self-engaging with the latch to hold it in latched condition retaining the door, and unlatching means selectively operable to disengage the latching pawl for opening the door, said unlatching means comprising a pawl lifter moveable from a position of rest to carry the latching pawl out of engagement with the latch, and a power driven output member selectively movable to engage and displace the pawl lifter from said position of rest; characterised in that said output member is a plunger advanced and retracted by a drive motor and also displaceable laterally to an inactive angular position at which it does not engage with the pawl lifter, and in that the unlatching means further includes guide means controlling the path of movement of the plunger including a track formation on one of the plunger and a stationary part of the assembly coacting with a follower on the other of said plunger and part to cause the plunger to be displaced to said inactive position during retraction from its advanced position whereby, if power should fail during retraction, manual operation of the pawl lifter for unlatching will not be obstructed by the plunger.
Preferably the assembly further includes an over-riding formation operated independently of the plunger by manual shifting of the pawl lifter, to displace the plunger to the inactive position if power should fail during advance or at the advanced position so that said manual shifting is not blocked by the plunger when not displaced by the follower and track formation.